@article{JS:SC:MY:09:journal,
author = {Jimmy Sastra and Sachin Chitta and Mark Yim},
title = {Dynamic Rolling for a Modular Loop Robot},
journal = {The International Journal of Robotics Research},
volume = {28},
number = {6},
pages = {758-773},
doi = {10.1177/0278364908099463},
year = {2009},
abstract = {Reconfigurable modular robots have the ability to use different gaits and configurations to perform various tasks. A rolling gait is the fastest currently implemented gait available for traversal over level ground and shows dramatic improvements in efficiency. In this work, we analyze and implement a sensor-based feedback controller to achieve dynamic rolling for a loop robot. The robot senses its position relative to the ground and changes its shape as it rolls. This shape is such that its center of gravity is maintained to be in front of its contact point with the ground, so in effect the robot is continuously falling and thus accelerates forward. Using simulation and experimental results, we show how the desired shape can be varied to achieve higher terminal velocities. The highest velocity achieved in this work is 26 module lengths per second (1.6 m/s) which is believed to be the fastest gait yet implemented for an untethered modular robot. One of the major findings is that more elongated shapes achieve higher terminal velocities than rounder shapes. We demonstrate that this trend holds going up inclines as well as down. We show that rounder shapes have lower specific resistance and are thus more energy efficient. The control scheme is scalable to an arbitrary number of modules, shown here using eight to 14 modules. },
url = {http://jimmysastra.com/wp-content/uploads/publications/rolling_dynamics.pdf},
eprint = {http://ijr.sagepub.com/cgi/reprint/28/6/758.pdf}
}

@inbook{JS:SC:MY:09:book, Abstract = {Reconfigurable modular robots use different gaits and configurations to perform various tasks. A rolling gait is the fastest currently implemented gait available to a modular robot for traversal of level ground. In this work, we analyze and implement a sensor-based feedback controller to achieve dynamic rolling for a 10 module loop robot. The controller exploits the dynamics of the system to build up momentum in each step by specifying a desired global shape for the robot at touchdown. Energy is input into the system both by raising the height of the center of mass of the robot and moving the position of center of mass with respect to the ground to maximize the moment arm due to gravity. Using simulation and experimental results, we show how the desired shape can be varied to achieve higher terminal velocities. Through simulation, we also show rounder shapes have lower specific resistance and are thus more efficient. },
Author = {Jimmy Sastra and Sachin Chitta and Mark Yim},
Date-Added = {2009-07-13 15:10:25 -0400},
Date-Modified = {2009-07-13 15:10:25 -0400},
Title = {Experimental Robotics},
M3 = {10.1007/978-3-540-77457-0{\_}39},
Pages = {421--430},
Chapter = {Dynamic Rolling for a Modular Loop Robot},
Series = {Sprinter Tracts in Advanced Robotics},
Publisher = {Springer},
Ty = {CHAPTER},
Year = {2008},
Bdsk-Url-1 = {http://dx.doi.org/10.1007/978-3-540-77457-0_39}
}